Effect of pyridine nucleotide precursors on the permeability of toad bladder in the presence of vasopression, adenosine 3':5'-cyclic monophosphate, and theophylline.

The increase and prolongation of water movement in the toad bladder in the presence of the pyridine nucleotide precursors adenine and nicotinamide (when stimulated with vasopressin, adenosine 3':5'-cyclic phosphate, or theophylline) suggests that pyridine nucleotides may be actively involved in membrane permeability.